Folic acid, or vitamin B9, derives its name from the Latin word folium, which was used to indicate large-leafed plants rich in folic acid. Naturally occurring in spinach leaves, this complex acid was first synthesized in 1945. Since then, mounting scientific evidence has demonstrated its beneficial effects on the human body. An essential nutrient for well-being and health, folic acid intake during pregnancy is especially important for preventing neural tube defects. This focus highlights the importance of correct intake levels of folic acid, particularly in subjects at risk of vitamin B(9) deficiency.